Fig. 3. Relationship between the metabolic power requirements of swimming and swimming speed for bluegill sunfish. Filled symbols, total metabolic power, P_gross; open symbols, P_net (total metabolic power minus standard metabolic rate); black symbols, labriform swimming; red symbols, undulatory swimming. Data are fitted with the following power relationships: labriform P_gross=0.47+6.45U^2.02; undulatory P_gross=0.61+29.6U^3.17; labriform P_net=0.12+3.29U^1.57; undulatory P_net=0.35+37.4U^3.47, where U is swimming speed in m s^–1. The broken lines show 95% confidence intervals for the fitted relationships. Values are means ± s.e.m., N=9, except where the speed ranges for labriform and undulatory swimming overlap at 0.25 m s^–1, where N=4 for labriform swimming and N=5 for undulatory swimming.